package org.gcube.common.scope.impl;

import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Pattern;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;

import org.gcube.common.scope.api.ServiceMap;
import org.reflections.Reflections;
import org.reflections.scanners.ResourcesScanner;
import org.reflections.util.ClasspathHelper;
import org.reflections.util.ConfigurationBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Scans the classpath for {@link ServiceMap}s.
 * @author Fabio Simeoni
 *
 */
class ServiceMapScanner {

	private static Logger log = LoggerFactory.getLogger(ServiceMapScanner.class);
	
	/**
	 * The path used to find service map configuration files.
	 */
	static final String mapConfigPattern = ".*\\.servicemap";
	
	/**
	 * Scans the classpath for {@link ServiceMap}s.
	 */
	static Map<String, ServiceMap> maps() {
		
		Map<String, ServiceMap> maps = new HashMap<String, ServiceMap>();
		
			try {

				JAXBContext context = JAXBContext
						.newInstance(DefaultServiceMap.class);
				Unmarshaller um = context.createUnmarshaller();

				// we include urls specified in manifest files, which is required
				// when we run tests in surefire's forked-mode
				ConfigurationBuilder builder = new ConfigurationBuilder().setUrls(
						ClasspathHelper.forManifest(Utils.urlsToScan())).setScanners(
						new ResourcesScanner());

				Reflections reflections = new Reflections(builder);

				for (String resource : reflections.getResources(Pattern
						.compile(mapConfigPattern))) {
					URL url = Thread.currentThread().getContextClassLoader()
							.getResource(resource);
					log.trace("loading {} ", url);
					DefaultServiceMap map = (DefaultServiceMap) um.unmarshal(url);
					maps.put(map.scope(), map);
				}
			} catch (Exception e) {
				throw new RuntimeException("could not load service maps", e);
			}
			
			return maps;
		}
}